Alcohol dependency is a syndrome that develops in alcoholics who, all at once, stop consuming alcohol. Minor symptoms include tremor, weakness, sweats, and nausea. The most severe cases include convulsions and hallucinations. If untreated, alcohol withdrawal may cause delirium tremens.
The customary treatment of alcohol dependency includes the administration of vitamin B and C complexes, benzodiazepines (to calm agitation and to help prevent dependency), and, sometimes, disulfiram (to prevent alcohol use). A review of the various pharmacological treatments existing for the treatment of alcohol dependency can be found in A Practice Guideline for the Treatment of Patients With Substance Use Disorders: Alcohol, Cocaine and Opioids, produced by the Work Group on Substance Use Disorders of the American Psychiatric Association and published in Am. J. Psychiatry 152:11, November 1995 Supplement. An updated review of the treatment of alcohol dependency was made by Mayo-Smith et al., JAMA Jul. 9, 1997, Vol. 278, No. 2, who conclude by indicating that the benzodiazepines (alprazolam, diazepam, halazepam, lorazepam or oxazepam) are agents suitable for the treatment of alcohol dependency, whereas β-blockers (propranolol), neuroleptics (chlorpromazine and promazine), clonidine and carbamazepine, may be used in coadjuvant therapy, but their use is not recommended as a monotherapy. In, none of the reviews mentioned is the use of flumazenil considered in the treatment of the alcohol withdrawal syndrome.
Flumazenil [ethyl 8-fluoro-5,6-dihydro-5-methyl-6-oxo-4H-imidazol[1,5-a][1,4]benzodiazepine-3-carboxylate] is a benzodiazepine antagonist which selectively blocks the effects exerted on the central nervous system via the benzodiazepine receptors. This active principle is indicated to neutralize the central sedative effect of the benzodiazepines; consequently, it is regularly used in anesthesia to end the general anesthesia induced and maintained with benzodiazepines in hospitalized patients, or to stop the sedation produced with benzodiazepines in patients undergoing brief diagnostic or therapeutic procedures on an inpatient or outpatient basis.
Some clinical studies have examined the role of flumazenil in the reversal of alcohol withdrawal syndrome.
Gerra et al., 1991, Current Therapeutic Research, Vol. 50, 1, pp 62-66, describe the administration to 11 selected alcoholics (who did not have cirrhosis, metabolic disorders, convulsions, addictions to other substances or psychiatric disorders) of 2 mg/day of flumazenil divided into 4 doses (0.5 mg), intravenously (IV), in saline solution, every 6 hours for 48 hours, continuing the treatment with flumazenil for 2 more days. The use of 0.5 mg of flumazenil is based on the presentation of pharmaceutical preparations that contain said active principle, for example ANEXATE7 [sic] ROCHE, but not on studies performed in humans concerning the level of occupation of the receptors involved. Taking into consideration the fact that the half-life of flumazenil in the human body is approximately 45 minutes, the administration of 0.5 mg of flumazenil every 6 hours (i.e., 0.08 mg/hour of flumazenil) does not seem adequate to effectively cover the cerebral benzodiazepine receptors (Savic et al., Lancet, 1991, 337, 133-137), which confirms what was stated by Gerra et al., loc. cit., who, on page 64, next to last paragraph, state that they did not observe significant changes in either the blood pressure or in the heart rate of the patients after the administration of flumazenil, which is surprising when there had been an effective interaction of the fumazenil administered with the cerebral benzodiazepine receptors. The tests performed by Gerra et al. present some characteristics that are far from the actual circumstances, for example, the tests were performed on a small sample (11 individuals) of select patients not representative of the pathology considered since it is relatively customary that these patients have cirrhosis, metabolic disorders, convulsions, addictions to other substances (cocaine, heroin, etc.) and/or psychiatric disorders. Moreover, Gerra et al. do not present data concerning the evaluation of the dependency either before or after administration of the drug. The treatment with flumazenil, in accordance with the protocol developed by Gerra et al., lasts 4 days, which means a very long period of time which causes inconvenience for the patient as well as an increase in the cost and duration of the treatment.
Nutt et al. [Alcohol & Alcoholism, 1993, Suppl. 2, pp 337-341. Pergamon Press Ltd.; Neuropschychopharmacology, 1994, Vol. 10, 35, part 1, Suppl., p. 85f) describe the administration to 8 alcoholics in the acute withdrawal phase of 2 mg of flumazenil, by IV, for 1 minute. This dosage was selected on the basis of studies that demonstrated that with said dose approximately 75% of the cerebral benzodiazepine receptors are occupied (Savic et al., Lancet, 1991, 337, 133-137). The results obtained after the administration of flumazenil were not completely satisfactory since in some cases, there was an immediate worsening of the withdrawal symptoms, especially of sweats and anxiety. In other cases, the withdrawal symptoms disappeared but returned a few hours later. Since flumazenil is metabolized and eliminated very quickly, the IV administration of a relatively high quantity of fumazenil in a single dose of 2 mg, for 1 minute, has several disadvantages since, on the one hand, it triggers side effects, and, on the other, some of the flumazenil administered yields no pharmacological response or a weak response which means an unacceptable expense.
The tests performed by Gerra et al. and by Nutt et al., loc. cit., with flumazenil to treat alcohol dependency do not provide representative results due to the use of a very small sample (only 19 patients tested of the approximately 600,000 patients treated annually in the United States during the years 1991-1994, years during which the work of Gerra et al. and of Nutt et al. occurred) which is not representative of said patients (the 11 patients treated in the trial of Gerra et al. were selected alcoholics who did not have cirrhosis, metabolic disorders, convulsions, addictions to other substances or psychiatric disorders). Moreover, the results obtained are not conclusive since in some cases, no significant changes were observed in either the blood pressure or the heart rate of patients after the administration of flumazenil (Gerra et al., loc. cit.); whereas, in other cases, an immediate worsening of the withdrawal symptoms was observed, especially sweats and anxiety (Nutt et al., loc. cit.). These very discouraging results seem to have favored the abandonment of flumazenil as a therapeutic agent for the treatment of alcohol dependency, a situation which could explain the absence of publications of new trials associated with the treatment of alcohol dependency with flumazenil during the past 6 years as well as the failure to include said treatment in the aforementioned reviews concerning the treatment of alcohol dependency [A Practice Guideline for the Treatment of Patients With Substance Use Disorders: Alcohol, Cocaine and Opioids and Mayo-Smith et al.].
Consequently, it would be desirable to be able to determine without ambiguity whether flumazenil may be a suitable agent to treat alcohol dependency and, if so, to develop a protocol for administration of flumazenil for the treatment of alcohol dependency that would enable effectively eradicating the symptoms of alcohol withdrawal. It would also be desirable to reduce the quantity of flumazenil to be administered per dose during a short period of time for the purpose of reducing, on the one hand, the risk of undesirable side effects, and, on the other, to reduce or avoid unnecessary and pointless consumption of flumazenil.